@katainaka0503, thanks for your PR! By analyzing the history of the files in this pull request, we identified @alexandrudima and @rebornix to be potential reviewers.

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I am not sure what 509th line and 510th in extensions/markdown/syntaxes/markdown.tmLanguage mean.

<key>comment</key>
<string>Currently does not support un-indented second lines.</string>

If this comment means this

- aaa
(empty line)
    - bbb
(empty line)
    - ccc

is not properly colored,
maybe this comment should be deleted.

(this was repost from #19596 )

Thanks for the contribution. This will be in the 1.10 vscode insiders builds once we start those up again